As video display apparatuses, there are various kinds of apparatuses such as a TV receiver, a monitor, a projector and the like. Video data outputted from a video output apparatus that is connected to a front stage thereof may be inputted to a video display apparatus (hereinafter, it may also be described as “video input”), and a video may be displayed on its own screen on the basis of the video data (hereinafter, it may also be described as “image output”). Further, the video display apparatus may output the video data to an external video display apparatus that is connected to a rear stage thereof (hereinafter, it may also be described as “video output”), and the external video display apparatus is caused to display the video on a screen.
As a communication interface between apparatuses including the video display apparatus, there is an HDMI (High-Definition Multimedia Interface). The HDMI is standard specification of a communication interface via which a digital signal of multimedia data containing data such as a video, an audio, and a command and information is transmitted between apparatuses. In apparatuses corresponding to the HDMI, HDMI connectors between the apparatuses are connected via an HDMI cable.
The HDMI contains a mechanism to transmit EDID (Extended Display Identification Data) between apparatuses. The EDID is apparatus information that contains a parameter value representing specification or performance of an apparatus, and contains resolution of video data (referred to also as a “screen pixel number” or the like) as one parameter value, for example. By transmission of EDID between connected apparatuses, authentication between apparatuses, determination of multimedia data to be inputted or outputted between apparatuses, and the like are carried out.
U.S. Pat. No. 7,358,928 (Patent Document 1) is cited as an example of prior art regarding communication between apparatuses including a video display apparatus.